Computer-implemented system and method for tracking entity location

ABSTRACT

A computer-implemented system and method for tracking entity locations is provided. Pieces of medical equipment are each associated with a tracker and monitored. A plurality of reader systems are positioned within a medical facility. A request for a location of one of the pieces of medical equipment is received. The reader systems are interrogated for the tracker associated with the piece of medical equipment. The location of the piece of medical equipment is determined within the medical facility based on those reader systems that identify the tracker associated with the piece of medical equipment. The location of the piece of medical equipment is provided in response to the request.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/099,569, filed Nov. 16, 2020, pending, which is a continuation ofU.S. Pat. No. 10,839,957, issued Nov. 17, 2020, the priority dates ofwhich are claimed and the disclosures of which are incorporated byreference.

FIELD

This application relates in general to tracking objects and, inparticular, to a computer-implemented system and method for trackingentity locations and generating histories from the locations.

BACKGROUND

Most hospitals are large organizations that provide medical care andtreatment to numerous patients. For example, in 2010, 35.1 millionindividuals were admitted to non-Federal short-stay hospitals in the U.Sand the average stay was 4.8 days. To ensure proper patient care, eachhospital must employ large numbers of individuals and maintain adequatetypes and numbers of medical equipment. Working in a hospital can bechaotic due to the nature of patient care, but can be furtherintensified by challenges stemming from the extreme numbers ofemployees, patients, and equipment that must be maintained andmonitored.

The challenges can include locating medical equipment, finding aparticular employee, and tracking patients. For example, some medicalequipment, such as IV pumps and defibrillators are used by multiplepatients, on an as needed basis. Some hospitals designate a singledefibrillator for each floor, and if the defibrillator is in use while adifferent patient on the same floor goes into ventricular fibrillation,another defibrillator must be obtained quickly and brought to thepatient to prevent brain damage and possibly death. However, doctors andnurses are often unaware whether a defibrillator is in use and may onlyfind out by physically going to the machine. The time spent looking foran available piece of critical equipment such as a defibrillator must beminimized to reduce damage to the patient and ensure high care quality.

With respect to employees, a doctor or other caretaker can be paged whenneeded for a medical emergency. However, if occupied, the doctor may notimmediately respond to the page and must be located. Time spent lookingfor a doctor or other medical professional to attend to the emergencycan be detrimental to the health of a patient and the outcome of theemergency. In addition to employees, a hospital must monitor patients toprovide treatment and ensure patient safety. For example, measures mustbe taken to prevent newborn babies from being mistakenly switched orabducted from the hospital. In a further example, patients sometimesleave the hospital on their own before finishing treatment or beingformally discharged and alerting the hospital staff when such asituation comes up may be of value if an intervention can be made toavoid the situation of a patient leaving the hospital before completingtreatment

There are existing approaches and equipment that assist hospitalsmonitor equipment, employees, and patients. For example, medicalequipment can be maintained using bar codes. A unique bar code isattached to each piece of medical equipment and the bar code is storedin a database with information about the medical equipment. However, useof bar codes only allows a user to look up information about thecorresponding piece of equipment, such as when the equipment was lastused or serviced, and fails to provide a location of the equipment.Infrared technology can be used to observe people; however, a directline of sight is needed, making the implementation of the infraredtechnology expensive and complex. Further, RFID tags are often attachedto babies via ankle bracelets and the tags are detected by monitorspositioned throughout the hospital. Yet, using a single RFID reader todetect an individual or object can, by itself, only determine thepresence or absence of that individual or object, not its precise realtime location and movement.

Therefore, there is a need for identifying real-time locations ofmedical personnel, patients, hospital visitors and equipment that isefficient and of reasonable cost. Moreover, the real-time locationsshould be stored in a database that can be queried later on in order todetermine a location history.

SUMMARY

A user can efficiently locate an entity within a hospital using alocator system that employs a tracker, such as an RFID tag. A uniquetracker is obtained and physically associated with a particular entityby affixing the tracker to the entity. Further, the trackeridentification (ID) information such a unique ID number is entered intoa database with identifying information regarding the entity such thatappropriate association between the location of the tracker and theentity being tracked can be made once the locator system is in use.

The locator system includes an array of RFID reader systems placed instrategically located nodes throughout the hospital. The nodes arelocated so the interrogation range of individual RFID reader systemsoverlap that of neighboring nodes. The location of an identified RFIDtag can then be determined by a basic triangulation method, or bycorrelating the signal strengths of different reader systems located atdifferent nodes for more precise location identification. RFID readersystems with tunable ranges can be used to improve accuracy and reducethe number of nodes needed. In one example, sweeping through the tunablerange by modulating the radio frequency (RF) power emitted by an antennaassociated with the reader and progressively identifying the tags thatcome into range could be used to pinpoint the location of specific tagsand corresponding vehicles. In another embodiment, the signal strengthassociated with individual tags could be used to estimate distance froma given reader node by looking up previously calibrated information onsignal strength and distance from a particular node, and thereby,improve the location tracking accuracy in addition to basictriangulation methods.

Readings by the reader systems are obtained to determine real timeentity locations and movement, which are then stored in the database.Subsequently, when a user needs to locate an entity, the user can accessa user interface on a display such as a TV screen, computer screen,smartphone or smartwatch and/or tablet computer screen, and enter anidentifier for the entity. The locator system then provides a locationof the entity to the user. The location can be obtained from thedatabase or can be determined upon the location request.

A further embodiment provides a computer-implemented system and methodfor tracking entity locations. Pieces of medical equipment are eachassociated with a tracker and monitored. A plurality of reader systemsare positioned within a medical facility. A request for a location ofone of the pieces of medical equipment is received. The reader systemsare interrogated for the tracker associated with the piece of medicalequipment. A location of the piece of medical equipment is determinedwithin the medical facility based on those reader systems that identifythe tracker associated with the piece of medical equipment. The locationof the piece of medical equipment is provided in response to therequest.

Still other embodiments of the present invention will become readilyapparent to those skilled in the art from the following detaileddescription, wherein is described embodiments of the invention by way ofillustrating the best mode contemplated for carrying out the invention.As will be realized, the invention is capable of other and differentembodiments and its several details are capable of modifications invarious obvious respects, all without departing from the spirit and thescope of the present invention. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a computer-implemented system fortracking entity locations and generating histories from the locations,in accordance with one embodiment.

FIG. 2 is a flow diagram showing a method for tracking entity locationsand generating histories from the locations, in accordance with oneembodiment.

FIG. 3 is a block diagram showing, by way of example, a wristband with atracker.

FIG. 4 is a block diagram showing, by way of example, a tracker on alanyard.

FIG. 5 is a block diagram showing, by way of example, a tracker on aclip.

FIG. 6 is a block diagram showing, by way of example, a piece of medicalequipment with a tracker.

FIG. 7 is a block diagram showing, by way of example, a hospital roomwith tracker readers.

FIG. 8 is a block diagram showing, by way of example, a floor plan of ahospital with multiple reader systems.

FIG. 9 is a flow diagram showing, by way of example, a process fordetermining entity location.

FIG. 10 is a block diagram showing, by way of example, a floor plan of ahospital with an identified entity.

FIG. 11 is a block diagram showing, by way of example, a graph of atracker within range of three reader systems.

FIG. 12 is a block diagram showing, by way of example, a floor plan of ahospital with multiple reader systems of various ranges.

FIG. 13 is a block diagram showing, by way of example, a floor plan of ahospital with multiple reader systems of various ranges, in a furtherconfiguration.

FIG. 14 is a block diagram showing, by way of example, a Web page forsearching for an entity location.

FIG. 15 is a block diagram showing, by way of example, a Web page of amap with an entity location.

FIG. 16 is a block diagram showing, by way of example, a Web page of amap with a location history.

FIG. 17 is a block diagram showing, by way of example, a chart for alocation history.

DETAILED DESCRIPTION

When a medical emergency occurs in a hospital, quickly locatingappropriate individuals and equipment needed to treat the emergency iscrucial to prevent further medical complications. Conventional methodsfor monitoring entities, such as people and equipment, fail to providereal-time locations and can still require a user to spend significanttime and energy locating the needed entity. The time spent searching foran entity can result in decreased efficiency, increased costs, andavoidable medical complications. Assisting a user to quickly and easilyfind people or equipment within a hospital can reduce the time spentsearching for an entity, which can increase hospital efficiency, whiledecreasing a number of medical complications and costs.

Tracking people and equipment helps to quickly locate people andequipment when needed. FIG. 1 is a block diagram showing acomputer-implemented system 10 for tracking entity locations anddetermining histories from the locations, in accordance with oneembodiment. A tracker 20 a-c is assigned to an entity (not shown)located within a hospital and an identity 15 of the tracker 20 a-c isentered into a computer 11 for transmitting to a server 13 via aninternetwork 12, such as the Internet or a local area network (LAN),including a wired Ethernet or a wireless (WiFi) network, and storing ina database 14 with identifying information 19 for the entity. The entitycan include an individual, such as a hospital employee or patient, ormedical equipment, as well as other types of entities. Meanwhile, thetracker 20 a-c can be disposable or reusable, and can be associated withan entity via an adhesive, a lanyard, a wrist or leg band, and a clip,as well as by other means. The trackers 20 a-c are further discussedbelow with reference to FIGS. 3-6.

Reader systems that can identify the trackers, such as through radiofrequency identification, are dispersed throughout the hospital and canbe affixed to walls and ceilings of the building. The reader systems canbe placed in strategically located nodes within the hospital and can useRFID technology to determine an entity's location. In one embodiment,the nodes are located so the interrogation range of individual RFIDreader systems overlaps that of neighboring nodes. The location of anidentified RFID tag can then be determined by a basic triangulationmethod, or by correlating the signal strengths of different readersystems located at different nodes for more precise locationidentification. Placement of the nodes is further described below withreference to FIGS. 8-12.

Once the tracker 20 a-c is associated with an entity, the reader systemscan search for and identify the tracker 20 a-c within range on aperiodic, continual, or as requested interrogation basis as the entitymoves throughout the hospital. The reader systems that identify thetracker at each interrogation are noted and a location of the entity isdetermined based on the reader systems that identify the tracker, thelocation of the reader systems, and the range of the reader systems.Once determined, the tracker locations are stored in the database 14with the time of interrogation for providing to a user as the entitylocation, upon request. The tracker locations can also be stored in aseparate database. In a further embodiment, the tracker location can bedetermined upon request by the user. Determining tracker and entitylocation is further discussed below with reference to FIG. 9.

To obtain the entity location, the user can enter a request in acomputer 10, 18, tablet (not shown), or mobile computing device (notshown), as well as any other device that can be interconnected to theserver 13 and database 14 via the internetwork 12. The computers 10, 18can be located throughout the hospital, with at least one computerlocated on every floor, such as at a nurse's station. Alternatively, orin addition to the computers, doctors, nurses and other hospitalemployees can utilize tablets or mobile computing devices to look up anentity location.

The entity location tracking system assists a user in finding entitiesthat are difficult to locate within the hospital. FIG. 2 is a flowdiagram showing a computer-implemented method 30 for tracking entitylocations and generating histories from the locations, in accordancewith one embodiment. A tracker is assigned to an entity (step 31) to betracked, including equipment or people within the hospital, includingdoctors, nurses, other employees, patients, and visitors, as well asother types of entities to be tracked within the hospital. The trackerscan be assigned to the entities randomly, in consecutive order, or by anemployee of the hospital or a third party. Subsequently, the tracker isconjoined with the entity based on the entity type. The tracker can bedirectly affixed to objects, such as furniture or equipment, orindirectly associated with people via a lanyard, clip, or bracelet. Forexample, a tracker printed onto an adhesive sticker can be directlyprovided on a piece of medical equipment, while patients may wear thetracker on a wrist band or ankle band, and doctors can wear the trackeraround their neck on a lanyard.

An identifier of the tracker is entered into a database withidentification information for the entity (step 32). The entityidentification information can vary based on a type of entity. Forexample, patient entity information can include name, hospital room, anddoctor, while visitor entities can include type of visitor andauthorized or unauthorized access to particular areas of the hospital,and equipment can include model number, make, and year of production.Other types of information are possible.

Once the tracker is associated with the entity, one or more readersystems located throughout the hospital can obtain readings (step 33)from the tracker based on a location of the tracker. Interrogation ofthe reader systems can occur at various times, such as on a periodic,continual, or as-requested basis. During each interrogation, readingsfrom the reader systems that identified the tracker can be processed todetermine a location of the entity. The location of the entity can bebased on the reader systems that identified the tracker, a reading rangeof those reader systems, and a location of those reader systems. Forinstance, a triangulation method can be applied to the data to identifyan approximate location or area in a vicinity of location of the entityby identifying overlapping zones of the ranges of the reader nodes thatare able to successfully communicate with the tracker. Alternatively,relative signals from the reader nodes that identify the tracker can beused to determine the tracker position, and thus, entity location withinthe hospital, in a more accurate fashion. Readers receiving a strongersignal are closer to the tracker than readers receiving weaker signals.Information on which overlapping reader nodes are within range of thetracker can only determine whether the tracker is inside the overlapregion. The relative strengths of received signals provide an extradimension for triangulating the precise location of the tracker withinthe overlap region. Determining a location of the entity is furtherdiscussed below in detail with reference to FIGS. 8-12.

When a user needs to quickly locate an entity, or obtain a past locationor location history for the entity, the user can enter identifyinginformation (step 34) for the entity into a computer. The identifyinginformation can include, inter alia, a name, identification number, makeand model, or date of birth, as well as other types of information. Uponreceipt by the computer, the identifying information is transmitted tothe server for identifying the associated entity and for determining thetracker (step 35) associated with the entity. If requested, a current orpast location of the entity is obtained (block 36). A current locationcan be determined upon receipt of the request or alternatively, a mostrecent location for the entity, which is stored in a database, can beused as the current location. When determined upon request, the readersystems are polled to identify those reader systems that obtain readingsfrom the tracker. Information regarding the reader systems that identifythe tracker is processed to determine a location of the tracker, such asby triangulation, as described above with respect to FIG. 1.

Further, if a location history for the entity is optionally requested, apath of the tracker associated with the entity is generated (step 37)based on the current and past locations for that tracker within aspecified range of time. The time range for the history can range fromhours, to days, to months, and to years. Other time ranges are possible.Once determined, the location of the tracker is designated as a locationof the entity (block 38) and provided to the user (block 39), along withthe history, if requested.

The entity location is determined as a location of the tracker so theentity and tracker must be closely associated. The type of associationbetween the entities and trackers can depend on a type of the entity, asdescribed below with reference to FIGS. 3-6. Further, a type of trackerto be associated with an entity is also dependent on the entity type.For example, patients temporarily reside at a hospital, while employeesare located at the hospital on a regular and generally, long term basis.Thus, disposable trackers can be provided to the patients, whilereusable trackers can be provided to employees. The disposable trackerscan be embedded in a disposable wrist or ankle band for attaching to apatient during the patient's hospital stay. Additionally, active tagscan be used for doctors to more accurately determine a location ofdoctor needed for an emergency, while passive tags can be used forequipment or patients to determine a vicinity or region within which theentity is located.

The trackers can be assigned and conjoined with the entities upon entryinto the hospital; however, other times are possible. Generally, when apatient is admitted to a hospital, a band with identifying informationis wrapped around the patient's wrist or ankle, and the tracker can beincorporated into the identification band itself. FIG. 3 is a blockdiagram showing, by way of example, a wristband with a tracker. Thewristband 50 can include a bracelet or strap that is secured around anindividual's wrist. The tracker 51 can be printed directly on thewristband 50, embedded within the wristband, or can be removablyaffixed, such as by adhesive, glue, or rubber. As well, the bracelet canbe made from plastic, vinyl, cloth, paper, or other materials, includingTyvek. Ankle bands can be made from the same material as the wristbandsor from separate material, and the tracker can be printed directly on,embedded in, or removably affixed to the ankle band.

As described above, the wrist and ankle bands can include identifyinginformation 52, such as the patient name, birth date, and admissiondate. Other types of identifying information are possible, including ababy's name, allergies, and room number. Upon admittance of a patient, aband embedded with a tracker can be printed with the patient'sidentifying information. However, if not embedded, the tracker can beprinted with the identifying information or a preprinted tracker can beaffixed to the band. The band is then applied to the patient for wearduring the patient's stay. When the patient is discharged, the band isremoved and disposed of for sanitation purposes.

In contrast to patients, hospital employees are generally at thehospital on a regular, long-term basis, and more permanent andpotentially more expensive trackers can be issued to the employees foruse during employment by the hospital. Conventionally, employees areissued an identification badge for identification verification bypatients and for access into restricted areas. The trackers can beprinted on, embedded in, or affixed to the badges, which are worn by theemployees. FIG. 4 is a block diagram showing, by way of example, atracker 61 on a lanyard 62. Specifically, the tracker 61 can be combinedwith an identification badge, which a hospital employee 62, such as adoctor or nurse, can wear around his neck via a lanyard 62.Alternatively, the employee may prefer to wear the badge clipped to hispocket or to the waistband of his pants. FIG. 5 is a block diagramshowing, by way of example, a tracker 70 hooked on a clip 71. The clip71 can be attached to a pocket or waist band of the employee 72 and holdthe badge to which the tracker 70 is embedded, printed on, or affixed.

In addition to individuals, a tracker can be used to monitor equipment.FIG. 6 is a block diagram showing, by way of example, a piece of medicalequipment 80 with a tracker 81. The tracker can be removably affixed tothe equipment via adhesive, such as glue or rubber, or by hook and loopmaterial. Alternatively, the tracker 81 can be embedded into theequipment, or printed or embossed directly on the equipment. As theequipment 80 moves throughout the hospital, reader systems can identifythe tracker. The location of the tracker 81 is then determined based onthe particular reader systems that identified the tracker during acommon interrogation, a location of the reader systems that identifiedthe tracker, and a reading range of those reader systems.

The reader systems can be systematically positioned in the hospital suchthat a tracker moving throughout the building is visible to one or moreof the reader systems. FIG. 7 is a block diagram showing, by way ofexample, hospital rooms 90 with multiple reader systems. The hospitalcan include a plurality of reader systems 91 to identify the trackersand determine a location of each tracker. Each reader system can includeat least one antenna and a reader. An antenna identifies the trackerswithin a particular range of the reader system 91, while the readerprocesses identification information of the tracker. In one embodiment,the antenna and reader can both be positioned on a ceiling of thehospital, as well as on a post or wall within the hospital. In a furtherembodiment, the antenna and the reader can be separately positioned (notshown). For example, the antenna can be located on a ceiling, while thereader is placed on or within a wall.

Placement of the trackers on an entity, as well as placement of thereader systems in the hospital should be considered together since acommunication path between the antennas and the trackers, within aparticular range, is required. In one example, communication between thetrackers and reader systems occurs via an unimpeded radio frequencycommunication. However, other types of communication are possible.

Placement of the reader systems with respect to other reader systemsshould also be considered. For instance, a location of a tracker can bebased on triangulation when three reader systems each identify a commontracker. Based on the location of the reader systems that identify thetracker and a known reading range of the reader systems, a generallocation of the tracker can be determined. FIG. 8 is a block diagramshowing, by way of example, a floor plan 100 of a hospital with multiplereader systems 101. The reader systems 101 can be positioned within thehospital such that each tracker is in view of at least three readersystems; however, other numbers of reader systems are possible. In thisexample, the reader systems are located throughout the hospital floor,including in the hallways, patient rooms, surgery room, and equipmentrooms, as well as in other locations on the floor. The reader systems101 each identify trackers within a predetermined range. The locationand range of those reader systems that identify a common tracker arethen used to determine the tracker location. Other methods fordetermining tracker location are possible and may require a differentconfiguration of the tracker reader systems.

Determining the location of a tracker can require identification of thetracker by one or more reader systems. FIG. 9 is a flow diagram showing,by way of example, a process 110 for calculating a location of a trackerusing identification information of multiple reader systems. On aperiodic, continuous, or as-requested basis, readings of the trackersare requested (step 111) and tracker identification information isobtained (step 112) by the reader systems. Those reader systems thatreceive identification information for a common tracker are identified(step 113). The location of the tracker is calculated (step 114) basedon a location of the reader systems that identify the tracker and on anoverlap zone determined by the known reading ranges of those readersystems. In one embodiment, triangulation can be used to determine thelocation. The determined location is then stored (step 115) for thetracker and the entity associated with the tracker.

Using triangulation, the location of an entity is calculated based ondata from at least three reader systems with overlapping ranges. FIG. 10is a block diagram showing, by way of example, a hospital floor 120 withmultiple reader systems 121 a-c identifying a tracker. The readersystems 121 a-c are installed, for example, on the ceiling of the floor,and those reader systems with a shorter reading range are positionedcloser together than reader systems with a longer reading range so thatthe range of at least three reader systems overlap, which can representidentification of a common tracker by each of the overlapping readersystems.

In this specific example, three reader systems 121 a-c are located in ornear surgery room 3A on the West wing of Floor 3. One reader system 121a is located in the middle of the surgery room, a second reader system121 b is located in a supply room within the surgery room, and a thirdreader system 121 c is located outside a wash room, in the surgery room.Each of the reader systems 121 a-c has a common reading range that isdesignated by a circle 122 a-c around the reader system 121 a-c. Otherreader systems with varying ranges can also be positioned throughout thehospital floor to identify trackers, as further discussed below withrespect to FIGS. 11 and 12. Moreover, as mentioned previously, thereader ranges need not be fixed, but can be varied by modulating theradio frequency power transmitted via the reader antenna, therebyenabling coverage of a larger area using fewer reader systems.

In this example, the reader systems 121 a-c each have a reading range122 a-c that covers an area with a 16 foot radius. Meanwhile, surgeryroom 3A is about 32 feet long by 28 feet wide. Other room sizes, readingranges, and reader system locations are possible. During aninterrogation, each of the reader systems 121 a-c requests readings fromtrackers within range of that reader system. The readings can includeidentification of a tracker located on an entity that is within range ofthat reader system. For example, each of the three reader systems 121a-c described above obtain readings from a common tracker 123 that canbe identified by a tracker number, name, or other identifier. A generallocation of the tracker 123 can be represented by identifying an areathat is defined by overlapping reading ranges of the three readersystems. The location designated by the overlapping reading ranges canbe calculated based on the location of the reading systems and theranges of the reading systems using triangulation.

The location of the tracker can be determined using known locations ofthe reader systems that identify the tracker and a signal strength fromthe tracker to each of the reader systems. FIG. 11 is a block diagramshowing, by way of example, a graph 25 of a tracker 126 within range ofthree reader systems 127 a-c. Each of the reader systems A 127 a, B 127b and C 127 c is associated with a known location coordinate representedby (x,y) 129 a-c, while a location of a tracker (T) 126 is unknown.However, the location of the tracker 126 can be determined based on theknown location coordinates 129 a-c of the reader systems 127 a-c thatidentify the tracker 126 and a distance of each reader system from thetracker. The distances of the reader systems from the tracker can bedetermined based on signal strength.

Specifically, a vector 128 a-c from the tracker 126 to each of thereader systems 127 a-c is formed, with a direction of the vector 128 a-cextending from the tracker 126 to the respective reader systems 127 a-c.Each vector equals the distance between the tracker and the respectivereader system. For instance, the vector for reader system A isrepresented as |{right arrow over (r)}_(AT)| 128 a, the vector forreader system B is represented as |{right arrow over (r)}_(BT)| 128 b,and the vector for reader system C is represented as |{right arrow over(r)}_(CT)| 128 c. Prior to calibration, each vector distance can berepresented by a signal strength, S_(A), S_(B), and S_(C) of each of thereader systems. Upon calibration, the coordinates of the tracker 126 canbe determined using the known distances of each reader system 127 a-cfrom the tracker 126 based on the signal strength and the knowncoordinates of the reader systems 127 a-c using the following equations:

$\begin{matrix}{Y_{T} = \frac{\begin{matrix}{{\left( {x_{A} - x_{B}} \right)\left\lbrack {x_{c}^{2} + y_{c}^{2} - x_{B}^{2} - y_{B}^{2} + \beta - \gamma} \right\rbrack} +} \\{\left( {x_{B} - x_{c}} \right)\left\lbrack {x_{A} + y_{A}^{2} - x_{B}^{2} - y_{B}^{2} + \beta - \alpha} \right\rbrack}\end{matrix}}{2\left\lbrack {{\left( {x_{B} - x_{c}} \right)\left( {y_{A} - y_{B}} \right)} - {\left( {x_{A} - x_{B}} \right)\left( {y_{B} - y_{c}} \right)}} \right\rbrack}} & (1) \\{X_{T} = \frac{x_{A}^{2} - x_{B}^{2} - \left( {\alpha - \beta} \right) + {\left( {y_{A} - y_{B}} \right)\left( {y_{A} + y_{B} - {2y_{T}}} \right)}}{2\left( {x_{A} - x_{B}} \right)}} & (2)\end{matrix}$

Each of the known distances |{right arrow over (r)}_(AT)| 128 a, |{rightarrow over (r)}_(BT)| 128 b, |{right arrow over (r)}_(CT)| 128 c, can bedenoted by √{square root over (α)}, √{square root over (β)}, and√{square root over (γ)} respectively. Therefore, a is represented by|{right arrow over (r)}_(AT)|², which is a known value based on thesignal strength of the tracker to the reader system A, β is representedby |{right arrow over (r)}_(BT)|², which is a known value based on thesignal strength of the tracker to the reader system B, and γ isrepresented by |{right arrow over (r)}_(CT)|², which is a known valuebased on the signal strength of the tracker to the reader system C.Meanwhile, the x and y coefficients are known location coordinates foreach of the reader systems A 127 a, B 127 b, and C 127 c.

Once determined, the location of the tracker 123 can then be provided toa user that requested a location of an entity associated with thetracker 123. Identifying an entity's approximate location, such aswithin a particular area of the hospital can be sufficient since theuser can locate the entity quickly. In the above example, the user wasable to identify the entity associated with the tracker as being inSurgery 3A room on Floor 3 in the West wing. More specifically, thetracker was identified as being in either the main surgery room, thewash room, or the supply room, but not the bathroom. The location can beprovided to the user as one or more room numbers, room names, or as adesignated section or area of the hospital.

Location accuracy can vary based on the types of reader systems, thelocations of the reader systems, and the ranges of the reader systems.For example, reader systems of various ranges can be used to broaden orrefine a location determined for an entity. FIG. 12 is a block diagramshowing, by way of example, a hospital floor 130 with multiple readersystems of various ranges identifying a tracker 123. Two or more readersystems of varying ranges can be placed together to determine a locationof an entity. For example, a shorter range 131 a-c reader system ispositioned adjacent to each of the reader systems of FIG. 10. Threelonger range 122 a-c reader systems 121 a-c each identify the tracker123, as well as a reader system 131 a with a shorter range 132 a. Basedon the reader systems that identified the tracker, an area in which thetracker is located is identified by an overlapping range area of each ofthe four reader systems. The actual location of the area can bedetermined, for example, by triangulation. In comparison with the readersystem arrangement provided in FIG. 10, the reader system configurationof the FIG. 12 narrows the location that the user has to look for theentity.

In a further configuration, shorter-range reader systems can beinterspersed with longer-range reader systems. FIG. 13 is a blockdiagram showing, by way of example, a hospital floor with multiplereader systems of various ranges in a further configuration. Forinstance, a short-range 142 reader system 141 can be located on aceiling of Surgery room 3A, just outside the supply room. Use of theshort-range 142 reader system 141 in this example, can refine thelocation results provided by the example discussed above with referenceto FIG. 10, which includes identification of the tracker in one of themain surgery room, wash room, or supply room. Adding the short-range 142reader device 141 to the three long-range reader devices 121 a-cdescribed in FIG. 10 narrows the location of the entity to the mainSurgery room 3A, as determined by the overlapping range areas of thefour reader systems. The location defined by the overlapping range areacan be determined via conventional methods, such as triangulation, andsubsequently provided to the user.

Alternatively, RFID reader systems with programmable polling rangesprovide additional flexibility for electronically reconfiguring thelocator system grid without physically relocating the reader systems.Such dynamic reconfiguration could be used for improving the locationaccuracy of specific trackers and also to compensate for variations inthe signal range caused due to building elements such as walls,structural beams, large metal objects such as fans and air conditioningsystem enclosures.

In a further embodiment, a single reader system can be positioned withineach room in the hospital and the location of the tracker can bedetermined via the single reader system associated with the room inwhich the entity is located. Other configurations of the reader systemsare possible.

The reader systems can obtain tracker readings to determine entitylocation on a regular, continuous, or periodic basis. As describedabove, the tracker readings for each tracker can include one or moretracker identities within range of each reader. Alternatively, if notrackers are located within the range of a particular reader, noreadings are obtained or a negative reading may be provided. The trackerreadings can be combined with reader information, including, a locationof the reader and a range of the reader, as entity data. Subsequently,the entity data is combined with entity data from other readers thatdetected the same tracker to determine a location of the tracker and theentity associated with the tracker. In one example, the readers arepositioned such that any location within the hospital is within range ofat least three reader systems so that triangulation can be used todetermine the tracker's location. However, different numbers and rangesof readers can be used, as well as different methods for determininglocation. Once determined, the locations associated with an entity arestored in a database for access by a user.

The user can access the entity locations via a user interface, such as aWebsite. FIG. 14 is a block diagram showing, by way of example, a SearchWebsite 150 for searching for an entity location. The Website caninclude a home tab 151, a locator tab 152, an alert tab 153, a reporttab 154, and an administration tab 155, as well as other tabs. A Webpage associated with the home tab 151 can include the hospital name andlogin information for the user, including user name and password. In oneembodiment, only those users who are registered and authorized toconduct an entity search will be allowed to access the tabs, other thanthe home tab. Further, an access list can be maintained to identifythose entities for which a particular user is able to access locationinformation. For instance, a visitor may only be able to accessadministrative medical personnel, while a nurse is able to access allemployees and equipment within the hospital. The access list can includean identity of each registered user and a list of entities for whom theregistered user is able access locations.

After the user has been validated by his user name and password, theuser can conduct a search for a particular entity using the locator tab152. The Web page associated with the locator tab 152 can include asearch field 156 for the user to enter an identity of the entity whoselocation is to be determined. The identity can include a name, make,model, or other identifier. In one example, Dr. Smith is required toperform an emergency surgery on a patient in room 232 on the secondfloor of the North wing and is not responding to calls over theintercom. At 2:50 p.m., Nurse Leslie logs into the Search Website 150via the home tab 151 and accesses the search field 156 via the locatortab 152. Nurse Leslie enters the words “Julie Smith” into the searchfield and subsequently selects an “enter” or “search button (not shown)to conduct the search.

During the search, the entity identifier entered by the user is comparedwith a database of entities to determine the entity associated with theidentifier. Subsequently, a location of the entity can be determinedupon the entity location request or can be obtained from the database.When the location is obtained from a database, the most recentlydetermined location can be located, obtained, and provided to the user.Returning to the above example, Dr. Smith's location was determinedevery 15 minutes since she started her shift at noon. Thus, Dr. Smith'slocation was first located within the hospital at 12:15 p.m., since shewas a little late, and again at 12:30, 12:45, 1:00, 1:15, 1:30, 1:45,2:00, and 2:15 p.m. At 12:15 p.m., Dr. Smith was determined to be in thestaff locker room on the first floor of the hospital in the South wing.At 12:30 p.m., Dr. Smith was determined to be in the hallway outside ofroom 333 on Floor 3 of the West wing. At, 12:45 p.m., Dr. Smith waslocated in the wash room on the third floor of the West wing preparingfora surgery. At 1:00, 1:15, 1:30, 1:45, 2:00, and 2:15 p.m., Dr. Smithwas located in surgery room 3A on the third floor of the West wingperforming an appendectomy.

Nurse Leslie requested the location of Dr. Smith at 2:50 p.m. The mostcurrent location, in surgery room 3A, obtained for Dr. Smith at 2:45p.m. can be provided to the requesting user as Dr. Smith's currentlocation. Alternatively, the location can be newly obtained at the timeof the request. For instance, a request for tracker readings can betransmitted to the reader systems on an ‘on-demand’ basis and a newlocation of Dr. Smith can be determined and provided to nurse Leslieupon request.

When the user enters the identification information for the entity inthe search field, the user can also select whether he wishes to obtainthe most recently determined location or a newly determined location.Alternatively, the hospital can make the determination as to providingthe most recently determined location or a newly determined locationdepending on the urgency of the request, for example, whether thelocation request is in relation to an emergency situation requiring aparticular doctor or surgeon or whether the request is for a non-urgentmatter. Further, a determination of which location, the most current ornewly defined, can be determined based on a threshold. For instance, themost recently provided location can be provided when the time differenceof the most recently provided location and time of request by the usersatisfies a predetermined threshold.

Returning to the above example, the predetermined time threshold is sixminutes. The time difference between the most recently determinedlocation of Dr. Smith at 2:45 p.m. and Nurse Leslie's request at 2:50p.m. is five minutes. Thus, the difference of five minutes is less thanthe six minute threshold so the most recently determined location of Dr.Smith will be provided to the user. If the time difference exceeds thethreshold, a new location can be determined. Other thresholds can beused. However, the threshold should be small enough that the entity doesnot move too far from his most recently determined location, so the usercan easily find the entity based on the most recently determinedlocation.

Once determined, the location of Dr. Smith is provided to the requestinguser and can include one or more of a room number or name, a floornumber, or a wing of the hospital, as well as other locationinformation. Alternatively, or in addition, the entity's location can bepresented on a map. FIG. 15 is a block diagram showing, by way ofexample, a Web page 160 of a map 161 with an entity location 163. Themap 161 can be provided as a pop-up window or as a separate Web page,such as under the locator tab or a separate tab. Other presentations ofthe map are also possible. The entity associated with the tracker whoselocation was determined can be represented by an icon, avatar, text box,or other representation.

Returning to the above example, the location of Dr. Smith is determinedto be in surgery room 3A. An icon, representing Dr. Smith, is positionedon the map in the middle of surgery room 3A, where Dr. Smith isperforming the appendectomy.

An entity box 164 can be presented with the entity representation andcan include information about the entity. The entity information caninclude an identifier, location, job title, security access, campus orbuilding, and availability status, such as available or occupied, aswell as other information. Additionally, the entity box 164 can includea photograph or drawing 165, of the entity, which can be helpful if theuser must physically locate the entity and has not previouslyencountered the entity.

Returning to the above example, Dr. Smith is needed to perform anemergency surgery. After Nurse Leslie enters Dr. Smith's name into thesearch field, Dr. Smith's location is determined to be surgery room 3Aon floor 3 of the West wing. Subsequently, Nurse Leslie personally sendsa message to Dr. Smith in the surgery room, such as a by a privateintercom system or a direct line to the surgery room, or physically goesto the surgery room to request that Dr. Smith perform the emergencysurgery.

In addition to the entity location, a history of the entity's locationscan be provided over a predetermined time period or a user-selected timeperiod. The history can be provided as a list of times and locations oras a path on a map. FIG. 16 is a block diagram showing, by way ofexample, a Web page 170 of a map 171 with an entity path 172. A timeperiod for the history is determined and the locations associated withtimes within the history time period are plotted on the map to create apath 172. The time period can be selected by the user or automaticallydetermined. Additionally, information can be provided to the user toassist in selecting the time period. For instance, the entity's schedulecan be provided so that the user can select a day, shift, week, or othertime period for the entity's history.

The plotted locations 173 a-b of the path 172 can be represented on themap by circles or other shapes. Subsequently, the path 172 of the entitycan be filled in by further circles 174 or by drawing a line (not shown)through each of the circles. A larger circle around the plotted circlescan distinguish the determined locations 173 a-b from the circles thatare used to fill in the entity's path. The representation 171 of theentity is displayed on the map at the most recently determined locationto show the entity's current location.

Different history maps can be provided for different time periods ordifferent area within the hospital. For example, a map can be displayedfor each shift if the entity is a hospital employee. Also, if the entitymoves between different floors or wings within the hospital, a differentmap of the area may be used. In some embodiments, a three-dimensionalmap can be used.

Alternatively, an entity history can be provided to a requesting user asa chart of times and locations. FIG. 17 is a block diagram showing, byway of example, a chart for an entity history. The chart can includeentity information, such as an identifier, location, job title, securityaccess, campus or building, and availability status, such as availableor occupied, as well as other information. Additionally, the chartincludes a history of the entity, which is represented as a series ofconsecutive times and locations determined for the entity within aparticular time range.

In one embodiment, the frequency of locations for inclusion of thehistory can be selected by the user. For instance, during a yearlyinventory, a history is pulled for a particular ultrasound machineduring the year 2013. Instead of returning times and locations for atime period of 15 minutes over the whole year, a single location can beprovided for each day, for example. The location can be determined asthe place where the equipment was located for the most time during thatday or can be a new location, such as when the equipment was moved.

The location histories provide helpful information for trackingentities, such as a baby that has been taken from the maternity ward ora hospital visitor that has entered unauthorized areas. For example,areas where the baby is likely to be located can be stored with thetracker identification so that if a baby is determined to be outside oneof the authorized areas, an alarm can sound to indicate the baby hasbeen moved or taken. The location history can provide a path of the babythroughout the hospital and can be used to locate the track the baby.Also, the tracking of hospital staff can be used to automaticallyauthenticate computer systems after detecting a presence of anauthorized staff member so that appropriate data, such as patient datacan be displayed when the staff member is present.

Further, the histories can be used to determine how long an entity hasremained in one location. For example, a piece of equipment that hasremained in a supply closet for over a year may need to be recalibrated.Additionally, a patient who is capable of movement may not have movedfor a long period of time, which can indicate a fall. A time span duringwhich the entity remained at the location can be determined by locatingconsecutive times associated with a common location and determining atime difference between the most recent time and the earliest time. Thetime that an entity spends at a common location can be shown on the mapof FIG. 16, such as by a large dot or icon that gets larger the moretime the entity spends at the location. In one embodiment, a thresholdcan be applied to the time span at the location. When the time spanexceeds the threshold, an action can occur, such as an alarm sounding toindicate a possible patient fall or a need to calibrate a piece ofequipment.

Additionally, the location history can be used with other data todetermine whether the tracked entity has complied with a particularrequirement or to determine performance of the entity, as described infurther detail in commonly-owned U.S. Pat. No. 10,319,000, issued Jun.11, 2019, the disclosure of which is hereby incorporated by reference.For example, a location history of Dr. Smith can be obtained todetermine physician effectiveness and efficiency. Subsequently, thepatient schedule of Doctor Smith can be obtained. Together, the locationhistory and patient schedule can be used to determine how much of Dr.Smith's time at the hospital was spent with patients and the averagetime that Dr. Smith spent with each patient by calculating time spentwith patients using the location information, such as when Dr. Smith wasdetermined to be in patient exams rooms, and the time at which theappointments were scheduled. Further, the location history can be usedto determine whether an employee is working or taking a break. A breakcan be determined by identifying a location of an entity in the breakroom or by identifying the entity in an empty room or in non-patientrooms for a substantially long period of time.

The effectiveness of a doctor at treating patients can also bedetermined by comparing the location history with an outcome of patientvisits. For example, Dr. Smith saw eight patients on Jan. 4, 2014. Thefirst four patients were seen before lunch. The first patient came infor flu symptoms, the second and third patients came in for an annualexam, and the fourth patient had back problems. The amount of time spentwith each patient can be obtained from the location history and whenpaired with patient outcome, can be used to determine whether Dr. Smithis more efficient and effective than other doctors based on the amountof time spent and whether the patient was adequately helped or correctlydiagnosed.

In another example, the location history can be used to determinewhether a person has washed or cleansed his/her hands prior to meetingor seeing a patient by determining whether the person entered a handwashing station or whether the person entity stopped in front of a handsanitizing dispenser or station, and for how long the person remained atthe hand washing station or sanitizing dispenser. A threshold can beapplied to the amount of time spent at the station or dispenser todetermine whether the person actually washed his hands. In oneembodiment, the threshold can be at least 20 seconds. When the timespent at the station or dispenser exceeds the threshold, the personentity is determined to have washed her hands. However, if below, theperson entity likely did not wash her hands for a sufficient amount oftime or did not wash her hands at all.

The location histories can be used to identify actions for groups ofentities, and make a determination whether an entity action isconsistent with the group to which the entity belongs. For instance,patients who are immobile can be grouped together, as well as thosepatients that are partially mobile and fully mobile. The patients thatare mobile, but remain in one location for an unusually long period oftime may have fallen and cannot get up. To notify a caretaker, an alarmcan sound when the usually mobile patient has remained in the sameposition for a threshold amount of time. Whereas, a person that isimmobile is likely to remain in one location for long periods of time.In a further example, employees can be grouped into working andnon-working entities to determine whether those entities that areclocked in are working.

Although the tracking of objects has been described above with referenceto entities within a hospital, other objects can be tracked, such asindividuals, including children, or things, such as cars, books, officeor laboratory equipment, gym equipment, luggage, and toys, using relatedidentifier-tracker pairs, as described in further detail incommonly-owned U.S. Pat. No. 9,638,787, issued May 2, 2017, thedisclosure of which is hereby incorporated by reference. For instance,children can be tracked within a shopping mall so that if a parentaccidentally becomes separated from her child, a current location and apath of the child can be determined, and the parent and child can bereunited. In this example, a ticket having an identifier and a trackercan be provided to the parent. The parent retains the identifier andremovably affixes the tracker to the child, such as on a wristband or ashirt or hat of the child. Reader systems are positioned throughout theshopping mall and can take readings of trackers within a specified rangeon a periodic, continuous, or as-requested basis. The location of thetracker is calculated using data regarding the reader systems thatidentified that tracker and can be stored in a database. If the childbecomes separated from the parent, the parent locates a console to scanthe identifier. The tracker associated with the identifier is identifiedand the stored location of the tracker at one or more times can beprovided to the parent to track a route of the child. Additionally, afurther reading from the reader systems can be requested to identify acurrent position of the child so that the parent and child will bereunited.

Further, shopping habits of a consumer can be tracked within theshopping mall and can be used for directed advertising. For example, aretailer can affix a tracker to an item purchased by a consumer, whilemaintaining the identifier. Reader systems positioned throughout themall can identify the tracker as the consumer moves throughout theshopping mall. Based on locations of the tracker, a retailer canidentify the stores in which the consumer shopped to determine aspecific style or preference of that consumer.

In a further embodiment, drivers can efficiently locate their parkedvehicles using a parking locator system that employs a “smart” tickethaving one or more functional sections, including an RFID transponder(tag) section and a paired identification section, as described infurther detail in commonly-owned U.S. Pat. No. 9,638,787, issued May 2,2017, the disclosure of which is hereby incorporated by reference. Insome embodiments, the identification section can be a scannable QR code.In other embodiments, the identification section can be a bar code or asimple printed number. The identification section of the smart ticketidentifies the specific RFID tag associated with the ticket, which canbe issued to an individual vehicle when entering a parking structure.Before leaving a parked vehicle, a driver separates the two sections andleaves the RFID tag section on or in the vehicle, such as on the vehicledashboard or window. The driver keeps the identification section of theticket when exiting the vehicle. Upon the driver's return, theidentification section is used to look up the associated RFID tag. Thelocator system described in this application then finds the vehiclecontaining the identified RFID tag and provides the location of thevehicle to the driver.

Further still, the tracker can store information regarding the object tobe tracked or the individual tracking the item. For instance, cars canbe tracked within a parking facility by placing the tracker in a parkedcar. A photograph of the parked vehicle can be taken as the vehicleenters the parking facility. Image processing can be performed on thephotograph to determine a make, model, vehicle year, or license plate,which can be associated with the occupancy ticket. If the driver losesthe retained identification portion of the occupancy ticket, the drivercan enter the make, model, year, or license plate number of his vehicleto identify the tracker associated with that vehicle and the location ofthe tracker. Other information can be stored with the occupancy ticket,such as a time the driver entered the garage, which can be used toautomatically determine payment due for the time the vehicle was parkedin the facility. As well, frequent users of the garage, may associate abank account or credit card with their vehicles so that the informationcan be linked to the tracker for automatic payment upon entering orexiting the garage.

In yet a further embodiment, a user can take a photograph of theidentifier for later scanning if the user does not want to hold on tothe identifier provided by a dispenser. Alternatively, a camera locatedat the entrance of the parking facility can take a picture of the userand apply facial recognition software and techniques to associate theuser directly with the identifier. Then, the user may simply step infront of a console with a camera that can automatically recognize themand display the location of the vehicle.

To ensure that an entity can be accurately tracked, a network of readersystems, or nodes, must be strategically positioned throughout astructure in which the entity is to be tracked. The network of nodes canbe configured by calculating a range of each node and determiningspacing of the nodes based on the ranges so that each location withinthe structure is within range of at least one node. In a furtherexample, the nodes are strategically placed by range so that eachlocation in the structure is in the range of three separate nodes.However, just using range to configure the nodes is not always effectiveas most structures include walls and rooms with metal that can affectthe node ranges.

To account for different materials and equipment in the structure thatcan affect range, the nodes can first be placed solely on range.Subsequently, an active tag can be used to sweep the building and mapout the locations determined for the tag. The map can be used todetermine how many nodes detect each location determined for the tag andto reconfigure the nodes. If more than three nodes have identified thetag at some locations, the nodes can be moved further away from eachother to cover the structure using the least amount of nodes necessaryso as to reduce cost. In contrast, if two or less than two nodesidentify the tag, more nodes should be added within the structure toidentify a location using triangulation.

In a further embodiment, the location tracking system can include aprogramming mode in which an area of the structure is saturated withnodes. The area is swept with a tag and the system continuously turnsoff nodes to determine a minimum viable amount of nodes necessary fordetermining user location, such as through triangulation. Once thenecessary nodes for the area have been determined, the configuration ofnodes for a further area within the structure can be determined.

In yet a further embodiment, the nodes can be configured within an areaand to ensure that each location in the area is in range with three ormore nodes, the ranges of the nodes can be adjusted accordingly.Interrogation of the reader systems can depend of the type of objectbeing tracked. For instance, readings may be collected more often, suchas every minute, for individuals who move from location to location,than parked vehicles that do not move, for which readings can occurevery five minutes. Other time periods are possible.

While the invention has been particularly shown and described asreferenced to the embodiments thereof, those skilled in the art willunderstand that the foregoing and other changes in form and detail maybe made therein without departing from the spirit and scope of theinvention.

What is claimed is:
 1. A computer-implemented system for tracking entitylocations, comprising: trackers each associated with a piece of medicalequipment; a plurality of reader systems positioned within in a medicalfacility; a server comprising a central processing unit, memory, aninput port to receive the location data from the database, and an outputport, wherein the central processing unit is configured to: receive arequest for a location of one of the pieces of medical equipment;interrogate the reader systems for the tracker associated with the pieceof medical equipment; determine the location of the piece of medicalequipment within the medical facility based on those reader systems thatidentify the tracker affixed to the piece of medical equipment; andprovide the location of the piece of medical equipment in response tothe request.
 2. A system according to claim 1, wherein the centralprocessing system obtains a location of the piece of medical equipmenton a continuous basis or at predetermined times.
 3. A system accordingto claim 2, further comprising: a database to store the obtainedlocations.
 4. A system according to claim 3, wherein the centralprocessing unit performs the following: selects a most recent obtainedlocation from the database and provides the most recent obtainedlocation as the determined location of the piece of medical equipmentwhen a time difference between the most recent obtained location and therequest satisfies a predetermined threshold.
 5. A system according toclaim 3, wherein the central processing unit performs the following:determines a most recent obtained location from the database; identifiesa time at which the most recent obtained location was obtained;determines a time of the request; and determines a new location as thedetermined location of the piece of medical equipment when a timedifference between the time of the most recent obtained location and thetime of the request exceeds a predetermined threshold.
 6. A systemaccording to claim 3, wherein the central processing system generates ahistory for the piece of medical equipment based on a plurality of theobtained locations in the database.
 7. A system according to claim 1,wherein the central processing system receives with the request one ormore of a name, identification number, make, or model for the piece ofequipment.
 8. A system according to claim 1, wherein at least two of thereader systems comprise different signal ranges.
 9. A system accordingto claim 1, wherein the central processing system verifies an identityof the user prior to receipt of the request.
 10. A system according toclaim 1, wherein the central processing system determines anavailability of the piece of equipment based on the determined location.11. A computer-implemented method for tracking entity locations,comprising: monitoring pieces of medical equipment each associated witha tracker affixed to that piece of medical equipment; monitoring aplurality of reader systems in a medical facility; receiving a requestfor a location of one of the pieces of medical equipment; interrogatingthe reader systems for the tracker associated with the piece of medicalequipment; determining the location of the piece of medical equipmentwithin the medical facility based on those reader systems that identifythe tracker associated with the piece of medical equipment; andproviding the location of the piece of medical equipment in response tothe request.
 12. A method according to claim 11, further comprising:obtaining a location of the piece of medical equipment on a continuousbasis or at predetermined times.
 13. A method according to claim 12,further comprising: storing the obtained locations in a database.
 14. Amethod according to claim 13, further comprising: selecting a mostrecent obtained location from the database; and providing the mostrecent obtained location as the determined location of the piece ofmedical equipment when a time difference between the most recentobtained location and the request satisfies a predetermined threshold.15. A method according to claim 13, further comprising: determining amost recent obtained location from the database; identifying a time atwhich the most recent obtained location was obtained; determining a timeof the request; and determining a new location as the determinedlocation of the piece of medical equipment when a time differencebetween the time of the most recent obtained location and the time ofthe request exceeds a predetermined threshold.
 16. A method according toclaim 13, further comprising: generating a history for the piece ofmedical equipment based on a plurality of the obtained locations in thedatabase.
 17. A method according to claim 11, further comprising:receiving with the request one or more of a name, identification number,make, or model for the piece of equipment.
 18. A method according toclaim 11, wherein at least two of the reader systems comprise differentsignal ranges.
 19. A method according to claim 11, further comprising:verifying an identity of the user prior to receipt of the request.
 20. Amethod according to claim 11, further comprising: determining anavailability of the piece of equipment based on the determined location.